Research And Implementation Of Android Wireless Same Screen Technology

With the improvement of wireless technology and the generalization of intelligent projection,the demand of wireless same screen is increasing day by day,and the same screen technology is developing rapidly.Wi-Fi connects the devices in the wireless same screen system with each other to realize the content of small screen devices on large screen devices,which greatly facilitates the content sharing in people's daily life and work.As the connection mode between the same screen wireless devices,Wi-Fi has the characteristics of time-varying signal,serious interference of the same neighbor signal and so on,and the network congestion often occurs.In the case of network congestion,the rate adaptive ability directly affects the data volume of video stream,and the problem of large stream and small channel directly affects the picture quality of video playback.At present,the same screen function of Android large screen device only supports single type system and single device connection.For convenience,the same screen system that supports multi system type and multi device connection will be the future development trend.Based on the above considerations,this thesis implements a wireless one screen system based on the super terminal(Android projector)and Android smart phone,and solves the problem of picture quality and single device connection in the case of network congestion.The main work of this thesis is as follows:(1)This thesis studies the optimization of a rate control strategy for adaptive dynamic network transmission(ADNT).In order to guarantee the QoS(quality of service)of video streaming and improve the picture quality of the same screen,ADNT controls the bit rate on the basis of available bandwidth prediction.Compared with the traditional methods,ADNT improves the handover time and bandwidth utilization by 39.8%and 22.7%respectively,but it still has a certain degree of error in the prediction of available bandwidth in the case of congestion network,which leads to the improvement of the rate adaptive ability.To solve these problems,this thesis classifies the network state and improves the prediction accuracy of available bandwidth.On the basis of accurate prediction of available bandwidth,the rate control strategy is further optimized to fully improve the bandwidth utilization and ensure that the video stream can also maintain high-quality transmission in congested network.The test results show that the video quality of the optimized strategy is improved by 3%and 5%respectively compared with adnt in normal network and congestion network.(2)Design and implement a wireless same screen system supporting multi system type and multi device connection.The existing technology of the same screen is analyzed and compared,and the scheme of the system is designed with reference to the structure of miracast.The interface construction and instruction interaction between the client and the server of the system are completed,and the functions of the client audio and video data acquisition and coding,packet,transmission,decoding and reproduction of the server are realized.After a comprehensive test and analysis,the feasibility of the system and the same screen effect have reached the requirements of normal use.In this thesis,the design and implementation of wireless one screen system supporting multi system types and multi equipment connections are completed.The quality and delay of one screen under congestion network meet the requirements of teaching and meeting.In this thesis,the research of the rate adaptive strategy based on available bandwidth has a certain value for improving the QoS of media stream.